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16 The University of Kansas Paleontological Contributions-Paper 99
ington & Clark, 1971; Garden City Limestone,
Wasatch Range; Mason, 1975),
Oklahoma (upper Signal Mountain Limestone,
Wichita Mountains), Texas (uppermost
San Saba Member of Wilberns Formation and
lower Threadgill Member of Tanyard Formation,
Llano uplift), Pennsylvania-Maryland
(upper Stoufferstown Member of Stonehenge
Formation; Tipnis & Goodwin, 1972), and
Wyoming-Montana (Lower Ordovician of
Bighorn Mountains; Kurtz, 1978). Elsewhere,
C. angulatus is known from northwestern
Greenland (Stouge, 1977), Scandinavia (Lindstrom,
1955; Van Wamel, 1974), Soviet Union
(Viira, 1974), Australia (Druce & Jones, 1971;
Jones, 1971), and Iran (Müller, 1973). In
North America the species is found in Fauna B
(except lowermost part) and lower Fauna C of
Ethington and Clark (1971). LindstrOm (1955,
pl. 9) recorded C. angulatus through the upper
Tremadocian and into the lower Arenigian
of Scandinavia.
CORDYLODUS DRUCEI, new species
Figure 4K, M; Plate 1, figures 177, 20, 21, 25
Cordylodus angulatus Druce and Jones (part),
1971, p. 66, pl. 3, fig. 7 (not figs. 4-6).
Cordylodus cf. C. intermedius Abaimova
(part), 1975, text-fig. 8.42 (not 8.34), pl.
10, fig. 10.
(In part) Cordylodus oklahotnensis Druce and
Jones, 1971, p. 69, text-fig. 23j, pl. 5, figs.
6, 7; ?Jones, 1971, p. 47, pl. 2, figs. 5-8.
(In part) Cordylodus prion Druce and Jones,
1971, p. 70, text-figs. 23i, k-o, pl. 2, figs.
1 -7; not LindstrOm, 1955, p. 552, pl. 2,
figs. 14-16; not Müller, 1973, p. 33, textfig.
2E, 8, pl. 10, fig. 4; not Van Wamel,
1974, p. 59, pl. 1, figs. 8-9; not Viira,
1974, p. 63, pl. 1, figs. 6, 7.
not Cyrtoniodus prion Ethington and Clark,
1971, pl. 1, fig. 21; Miller, 1971, p. 79, pl.
1, figs. 14-17.
Holotype. -Rounded element, USNM
303283 (Fig. 4k; Pl. 1, figs. 20, 21).
Description. -Relatively rare species with
distinctive rounded element and somewhat
variable compressed element. Rounded element
asymmetrical with bulge (caria) on one
side of base beneath anterior end of denticulate
process; axis of bulge trending posteriorly
and downward. Cusp and denticles with
rounded edges; denticles separated at bases.
Basal cavity relatively shallow with apex extending
slightly above top of posterior process,
anterior edge concave or straight, apex
not recurved. Anterobasal corner a sharp
angle in primitive elements, but somewhat
rounded in more advanced elements.
Compressed elements less distinctive, may
include two forms. More distinctive form
asymmetrical due to lateral bending and to
presence of bulge (caria) on inner side of
base. Distinctive basal cavity curving concavely
on anterior edge, then bending sharply
near anterobasal corner and subparallel to
basal margin. Basal cavity moderately deep,
apex usually at least as high as top of posterior
process but may be shallower in advanced
elements. Second form symmetrical or nearly
so; cusp may be bent slightly to one side and
slight bulge (caria) may exist on inner side
near basal margin. Anterior edge of basal
cavity usually convexly curved and extending
about to top of posterior process. Both types
of compressed elements have laterally compressed
cusps and denticles with sharp edges;
denticles fused at bases.
Discussion. -Two rounded elements, one
illustrated by Druce and Jones (1971, pl. 3,
fig. 7) as C. angulatus and one illustrated by
Abaimova (1975, text-fig. 8.42, pl. 10, fig. 10)
as C. intermedius, have the distinctive characteristics
of the rounded element of C. drucei,
and they are here reassigned to this new
species.
The rounded element of C. drucei is
necessary to permit recognition of this species
because of the variability of the compressed
elements and their similarity to those of other
coeval species of Cordylodus. The asymmetrical
form is similar to the compressed element
of C. intermedius, and the symmetrical form
is similar to the compressed elements of C. angulatus
and C. rotundatus. The conclusion
that both types of compressed elements were
associated with the distinctive rounded element
of C. drucei is uncertain and is based on
the occurrence together of all three elements in
many samples.
Cordylodus drucei has three distinguishing
characteristics: a concave anterior edge of the